New data on pepsin mechanism and specificity.

Abstract

New data on the specificity and mechanism of action of porcine pepsin are presented, including statistical analysis of protein cleavage by the enzyme, kinetics of synthetic substrates, enzyme inhibition and activation, kinetics of transpeptidation reaction, and 180 exchange studies. From these data it was concluded that pepsin has an extended active site being able to accomodate specifically five amino acid residues of the substrate. The orientation of the substrate molecule relative to the ethanol binding loci in pepsin crystals has been determined. Pepsin mechanism includes "amino-enzyme" formation which chemically is not an amide, formed by the enzyme carboxyl with the amino fragment of the substrate.